In this specification, the term “database” is used to encompass a body of information formed by collating data items which have been selected according to appropriate criteria, and also to a more informal collection of data items which may be continuously changing and not under the control of a single authority, for example the body of information available from the internet or other public network.
A database user will usually require an arrangement for interrogating the database in order to identify data items of possible interest. The arrangement will typically involve software which interrogates the database in accordance with a search strategy entered by the user and which then provides to the user the results of that interrogation. Typically, these results will be in the form of a list of those data items retrieved identified as meeting the requirements of the search strategy. The order in which the data items are presented on the list is often unhelpful for identifying those of most interest, In the event that a large number of data items are listed, a user will need to conduct a further search with a narrower search strategy. In the event that no data items or too few data items are listed, a new search with a broader search strategy would be required. Formulation of these revised search strategies may be a matter of guesswork, to a significant degree. Consequently, although the interrogation arrangement may present results in a manner which gives the impression of sophistication, the quality of the results is dependent entirely on the search strategy and thus on the skill or imagination of the user. Inexperienced users may therefore find that inadequate or inappropriate results are produced, or that an unmanageable number of data items are identified. This can lead to frustration or disillusionment, deterring an inexperienced user from continuing to use the database.